1. Field of the Invention
This invention relates to a portable electronic apparatus such as a book shaped personal computer or a word processor and, more particularly, to a portable electronic apparatus comprising a synthetic resin housing containing therein various functional components such as a floppy disc drive, hard disc drive, and the like, and a method of assembling the same.
2. Description of the Related Art
Recently, there are known book or notebook-shaped portable computers having a flat box like base unit on which a keyboard and a display unit with a flat display panel are mounted.
A portable computer of the above identified type normally comprises a synthetic resin housing that provides a frame for a base unit and contains therein various functional components such as a floppy disk drive and/or a hard disc drive along with circuit board carrying thereon various circuit components. These functional components are normally supplied in the form of modules and placed in positions on the bottom wall of the housing, where they are then secured by means of screws to the bottom wall.
Upon assembling the conventional portable computers of this type, however, each of the functional components placed on the bottom wall is required to be independently secured by screws to the bottom wall. Thus, the attachment of the components is very troublesome, and thus, the assembling of the computer takes large time periods.
Further, the bottom wall of such a housing has a rather complicated profile because bosses for receiving screws should be provided on the bottom wall at positions on which functional components are placed. These bosses inevitably reduce the space inside the housing that can otherwise be used to accommodate components. In recent portable computers, it is desired that the housing is reduced in size in order to improve the portability of the computer. However, if the mounting space in the housing is reduced by the bosses, it is necessary to increase the size of the housing so as to increase the mounting space thereof, which opposes the requirement for providing a compact computer.
In addition to the various functional components, the housing of a portable computer contains therein a circuit board on which various circuit components are mounted. This circuit board normally has a rectangular shape substantially corresponding to the size of the bottom wall of the housing. So the space on the bottom wall is substantially occupied by the circuit board.
In order to improve the portability of the recent computers, it is required to reduce the length and the width of the housing. Thus, the mounting space in the housing tends to be further reduced in size, and forces the circuit board to be made further smaller. For solving this problem, there is proposed an arrangement wherein a single relatively large circuit board is divided into a plurality of small parts. The divided board are arranged in the housing such that they are overlapped with one another and connected to one another by means of flexible connecting boards.
Some of the circuit components carried by the circuit boards generate high frequency noises during operation. Such high frequency noises can interfere with wired as well as wireless telecommunications when leak out of the housing. Therefore, in conventional portable computers, the inner surface the housing of is normally coated with a conductive layer typically by plating so as to provide the housing with an electromagnetic shield effect. The circuit boards and other electronic components of the computer are enclosed with the conductive layer.
With such an arrangement, however, the circuit boards are apt to move relative to each other as they are connected together by flexible connecting boards, making the mutual connection of the boards unstable. This means that, when securing one of the circuit boards to the housing, it may accidentally shake the other circuit boards connected to it, causing them to hit and damage the conductive layer on the inner surface of the housing with their corners and edges and/or the components carried on them until eventually the conductive layer partly comes off from the cabinet and loses its electromagnetic shield effect.
In order to avoid such problem, it is necessary to carefully assemble the circuit board in the housing, thereby making the assembly troublesome. Additionally, the housing needs to be provided with a large number of bosses for screws for securing a plurality of circuit boards to the housing in a multilayered manner. Such additional bosses make the housing even more rugged and the efficiency of assembling a portable computer by using such a large number of screws to be driven into a rugged housing is inevitably low.
In a portable computer of the type under consideration, if a user desires to use application software and/or an application device, it is often required to be modified the computer by arranging additional components on the circuit substrates and/or replacing some of the existing components with improved ones in accordance with the application software and/or the application devices to be used. The multilayer arrangement of a plurality of circuit boards as described above then needs to be so devised as to facilitate such addition and/or replacement of circuit components without being disturbed by the circuit boards.
A portable computer of the above mentioned type is normally provided with a rechargeable battery pack for supplying power to the computer even when no commercial power supply is available. Such a battery pack may need replacement when it is time worn and has lost its rechargeability and therefore it is normally removably fitted to the base unit. In other words, the base unit of a conventional portable computer is provided with a storing space for storing a battery pack and a manually releasable lock mechanism for locking the battery pack in the storing space.
The lock mechanism comprises a knob with which the operator of the computer can control it by using a finger tip. The knob is usually exposed at a lateral side or the bottom of the base unit. The operator can release the lock mechanism by sliding the knob sideways with a finger tip and take the battery pack out of the base unit.
If the knob is exposed outside the housing, although it may be easily operable, it is subject to the danger of accidental release of the lock mechanism. Although the problem may be avoided by arranging a knob cover on the base unit, the provision of the knob cover gives rise to another problem of requiring a two-step operation of opening the cover or holding it in a position for exposing the knob and then sliding the knob before taking out the battery pack.
Furthermore, once the battery pack is recharged or replaced and put back in position, the knob cover needs to be slid back or reattached to the base unit, imposing an additional manual work on the operator. If the knob cover is not returned to its proper position, on the other hand, the knob remains in an exposed condition, leaving the lock mechanism unprotected against improper handling.
Portable computers are generally provided with expansion slots for receiving so-called expansion substrates for expansion features. In line with the recent trend of using card-shaped standardized substrates for expansion features, the PC Memory Card International Association (PCMCIA) in the U.S.A. has proposed four types of standardized cards as listed below.
Type 1: thickness 3.3 mm; type 2: thickness 5.0 mm; type 3: thickness 10.5 mm; thick type: thickness 18.00 mm.
Cards of types 1 and 2 are mostly used for IC memory cards that carry semiconductor memories thereon and find a variety of applications including those of security cards and cards of type 3 are often used as small card discs for I/O features, whereas cards of thick type find applications including those of I/O, LAN (local Area Network), FAX and modem features.
However, the fact that the PCMCIA has proposed such diverse standards clearly shows how standardization is difficult for cards of the sort discussed above. Particularly where portable electronic apparatuses need to meet the requirement of downsizing, it is extremely difficult to provide housings that are compatible with all standardized cards and at the same time satisfy the requirement of reduced outer dimensions of apparatus.